Device for dressing a grindstone to polish the running surface structure of a ski

ABSTRACT

The description deals with a facility for dressing of a grindstone ( 1 ) for grinding of a running surface structure of a ski, which facility consists of a rotating drive ( 7 ) for the grindstone ( 1 ), of a dresser ( 2 ) adjustable to the circumferential surface of the grindstone ( 1 ) and equipped with at least one cutting insert, and of a feed drive ( 6 ) for the axially parallel relative movement of the dresser ( 2 ) against the grindstone ( 1 ). To create favorable construction features it is suggested to provide a controlling system ( 8 ) for the feed drive ( 6 ) and/or the rotating drive ( 7 ), equipped with a control program memory ( 9 ) selectable via an input unit ( 10 ) and with an evaluation circuit ( 12 ) connected to the control program memory ( 9 ) for the program-sensitive definition of the position-dependent switching points for the rate of the feed drive ( 6 ) and/or the rotating drive ( 7 ).

CROSS-REFERENCE TO RELATED APPLICATIONS

Applicants claim priority under 35 U.S.C. §119 of Austrian applicationNo. A 52/98, filed on Jan. 16, 1998. Applicants also claim priorityunder 35 U.S.C. §120 of PCT/AT99/00009, filed on Jan. 12, 1999. Theinternational application under PCT article 21(2) was not published inEnglish.

FIELD OF INVENTION

The invention refers to a facility for dressing of a grindstone forgrinding of a running surface structure of a ski, consisting of arotating drive for the grindstone, of a dresser adjustable to thecircumferential surface of the grindstone and equipped with at least onecutting insert, as well as of a feed drive for an axially parallelrelative movement of the dresser against the grindstone.

DESCRIPTION OF THE PRIOR ART

In order to reduce friction between the running surface of a ski and thesnow on the one hand, and to be able to influence the water film formingbetween the running surface and the snow, running surfaces of skis arestructured. For this purpose various geometrical forms of runningsurface structures have been suggested, which are able to account forvarious conditions. To create the running surface structures formed byfinely divided grooves of the running surface, stamping tools are used,which, however, do not permit any variation of the given structure.Moreover, the displaced material of the running surface coating formsedge beads that have to be removed in an additional working cycle,otherwise these beads will adversely affect the running qualities of theski. Another factor is that the running surface structure produced bymeans of a stamping tool cannot be refined at will.

If a rotating grindstone is applied for machining the running surface ofa ski, the circumferential surface of which is provided with screwthread undercuts running in opposite direction, the running surface of aski can be ground to an appropriate structure by means of such agrindstone, which has the advantage that, apart from waxing or polishingof edges as required, any refinishing of the running surface becomesunnecessary. Moreover, the possible fineness of the running surfacestructure is limited only by the dresser for the grindstone, whichconsists of at least one cutting insert in the form of a true diamondprojecting towards the circumferencial surface of the grindstone. Fordressing of the grindstone, the dresser is to be moved axially parallelagainst the rotating grindstone, with the relative axial rate of feed ofthe dresser against the grindstone, together with the speed of thegrindstone, determining the pitch of the screw thread undercut cut intothe circumferential surface of the grindstone by means of the cuttinginsert. Via this pitch of the screw thread undercut, the fineness of thegrindstone structure and thus the fineness of the structure of a runningsurface of a ski machined by means of such a grindstone can bedetermined. By means of the known dressing devices for grindstones forgrinding of running surfaces of skis, essentially, it is only possibleto determine the fineness of the structure, but not a course of thestructure favorably adapted to the respective requirements depending ondifferent influencing variables like type of snow, snow temperature,type of coating of running surfaces, type of ski or skill of running ofthe user of the ski.

SUMMARY OF THE INVENTION

Therefore, the invention has the task to design a facility for dressingof a grindstone for grinding of a running surface structure of a ski ofthe above mentioned type in such a way, that grindstones for theproduction of manifold shapes and finenesses of structure can be dressedquickly and reproducibly to allow for the relevant given influencingvariables.

The invention solves the task by providing a controlling system for thefeed drive and/or the rotating drive, which controlling system isprovided with a control program memory selectable via an input unit andwith an evaluation circuit connected to the control program memory forprogram-sensitive definition of position-related switching points forthe rate of the feed drive and/or the rotating drive.

The invention is based on the finding that the webs remaining betweenthe intersecting screw thread undercuts running in opposite direction,the horizontal view of which is rhomboidal, form rows stretchingtransverse to the sense of rotation of the grindstone, and including anangle with the sense of rotation that depends on the ratio of pitches ofthe intersecting screw thread undercuts. In case of correspondingpitches of the intersecting screw thread undercuts, the rows of therhomboidal webs run vertical to the sense of rotation. In case ofdifferent pitches there is a corresponding gradient of these rhomboidalrows, depending on the pitch difference, which results in acorrespondingly inclined course of the running surface structure againstthe longitudinal axis of the ski. If the pitches of the screw threadundercuts in the circumferential surface of the grindstone in the areaof axial sections of the grindstone are varied, web rows of differentgradients—at least in some sections—against the sense of rotation willresult, with the effect that a running surface of a ski finished bymeans of such a grindstone, too, shows a structure with an inclinedcourse varying over the width of the running surface. As this course ofgradient of the structure sections repeating over the length of the skiis effective mainly on the formation of a water film between the runningsurface of the ski and the snow, the favorable gradient of the repeatingstructure sections of the running surface causes a good lateraldisplacement of water. For this purpose a control program memory isallocated to the controlling system for the feed drive and/or rotatingdrive, determining the pitch of the respective screw thread undercut, inwhich control program memory various control programs for givenstructural shapes of a running surface of a ski are stored, so that onlythe control program stored for a certain running surface structure mustbe selected via the input unit in order to preset the switching pointsfor the rate of the feed drive and/or the rotating drive via theevaluation circuit, connected to the program memory, of the controllingsystem. These switching points are calculated by the program anddetermine, as a function of the axial position, the variation of thepitch of the screw thread undercut, which is cut into thecircumferential surface of the grindstone by means of the true diamond.If, for example, the relative rate of feed of the dresser against thegrindstone during cutting of the screw thread undercuts running inopposite direction is reduced by a given amount at the longitudinalcenter of the grindstone with the initial speed remaining constant, thiswill result in a V-shaped course of the rows of the rhomboidal websbetween the intersecting screw thread undercuts. The gradient of theV-sides of these rows can be varied via the appropriate rate settings,while on no account implying symmetrical conditions. Additionally, thevariation of the gradient of the structures may be shifted from theaxial longitudinal center of the grindstone to allow for particularlyasymmetrial conditions for the displacement of the water film betweenthe running surface and the snow, as this may be favorable, forinstance, for cross-country skis, where, compared with alpine skis,there are particular, asymmetrical load conditions because of theskating technique. Of course, it is also possible for the pitch of thescrew thread undercuts to vary steadily along with the angle ofrotation, if required, for instance to be able to grind a wavy structureinto the running surface.

If the evaluation curcuit is connected to a program data memory forcharacteristic data for the control program to be selected via the inputunit as a function of the respective control program selected, controlcan be easily influenced via the presetting of characteristic data, sothat the control program can be adapted to the desired requirements ineach case. For example, via these characteristic data the gradientconditions of the sections of the running surface structure repeatingover the length of the ski, the fineness of the running surfacestructure or a possible lateral displacement of the selected structurecan be preset. These characteristic data inquired by the program andinput via the input unit are then preset via the program data memory ofthe evluation circuit to define the rate and the position-dependentswitching points for the rate of the feed drive and/or the rotatingdrive. As the only important factor is the relevant pitch of the screwthread undercuts cut into the circumferential surface of the grindstone,these pitches may be controlled either via the feed drive or therotating drive. But, of course, control via both the feed and therotating drive is possible, too.

Since, in case of different pitches of the screw thread undercuts, thevariation of the thread pitches must be determined in axial direction,an allocation of position between the dresser and the grindstone isnecessary. This allocation of position can be easily achieved byconstructional means in such a way that the controlling system isconnected to position switches for the feed drive, arranged according tothe axial length of the grindstone. Via these position switches, presetactual positions for the feed drive are transmitted to the controllingsystem, between which the feed control can be effected at sufficientaccuracy without any addtional position control. Of course, anadditional position control is possible, too.

BRIEF DESCRIPTION OF THE DRAWING

The drawing depicts an example of the subject matter of the invention,i.e. the facility for dressing of a grindstone for grinding of a runningsurface structure of a ski according to the invention is depicted in aschematic block diagram.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

According to the depicted example of embodiment, the grindstone to bedressed 1 is borne stationary, while the dresser 2 is provided on acarriage 3 displaceable parallel to the rotating axis of the grindstone1. The carriage 3 is moved via a threaded spindle 4 along the carriageguide 5 by means of a feed drive 6, which is designed as an electricmotor. The grindstone 1 is driven by a rotating drive 7, which, like thefeed drive 6, is controlled by means of a controlling system 8. The feeddrive 6 and the rotating drive 7 can be controlled via various controlporgrams stored in a control program memory 9 and selected via an inputunit 10. The boundary conditions of the individual control programs aredefined via characteristic data preset via the input unit 10, in orderto be able to adapt the selected control program according to therelevant requirements. Via the input unit 10, the characteristic data tobe preset are read into the program data memory 11, which provides thesecharacteristic data to an evaluation circuit 12, which calculates thereference variables for controlling the feed drive 6 and/or the rotatingdrive 7 and applies these reference variables to the controlling system8. Thus, via the evaluation circuit 12, the relevant rates for the feeddrive 6 and/or the rotating drive 7, as well as the position-dependentswitching points for any preset changes of rate are defined by theprogramm. Therefore, the grindstone 1 can be machined according to thesespecifications by means of the dresser 2. Via a position switch 13 forthe tool carriage 3, the starting position for adjustment of the dresser2 is recorded, the cutting insert of which, preferably a true diamond ora ceramic material, cuts a screw thread undercut into thecircumferential surface of the grindstone 1. The pitch of this screwthread undercut depends on the rate of feed of the dresser 2 and thespeed of the rotating drive 7 for the grindstone 1. To achieve a certainpitch of the screw thread undercut, these rates are preset via thecontrolling system 8, as a function of the selected control program andthe selected boundary conditions. If program-sensitive variations of thepitch of the screw thread undercut are intended, the rate of feed of thecarriage 3, for example, is changed, as soon as the switching pointpreset in the controlling system 8 is reached. The axial position of thecarriage 3 is then recorded via a rotary step transducer 14 of the feeddrive 6. The counter content of a counter connected to the rotary steptransducer 14, which is set ot a preset counter content via the positionswitch 13, indicates the axial position of the carriage 3, so that theposition-dependent switching points for the rate of the feed drive 6 canbe easily controlled via this position detection system. The feed drive6 is switched off after the program-sensitive changes of rate at the endof the feed travel monitored via the position switch 15, which resetsthe counter of the rotary steps back to a preset number to make up forpossible errors. After reversing the feed direction, a second screwthread undercut running in opposite direction is cut into thecircumferential surface of the grindstone 1, as a function of thealready cut screw thread undercut, to provide the circumferentialsurface of the grindstone 1 with a given structure of adjacentrhomboidal webs. The switching points for the change of the rate offeed, again, are effected via the controlling system 8, which isresponsible for a program-sensitive dressing of the grindstone 1, sothat by means of this grindstone 1 a running surface of a ski withselected structure can be ground.

Of course, the invention is not confined to the depicted example ofembodiment. For example, the grindstone 1 might be moved via a carriageopposite the stationary dresser 2 by means of its rotating drive 7, asthe only important factor for cutting a screw thread undercut into therotating grindstone 1 is the axial relative movement of the dresser 2against the grindstone 1. Moreover, the dresser might be equipped with acontrolled adjusting drive, so that an additional design possibility forthe running surface structure to be ground is achieved via the depth ofthe screw thread undercuts. Apart from that, the position switches 13,15 might also be assigned with the evaluation circuit 12, as this isoutlined in the drawing in short dashes. In this case, the relevant endpositions of the position control of the carriage 3 of the controllingsystem 8 are preset via the evaluation circuit 8. Moreover, the cuttinginsert of the dresser 2 might be aligned against the screw threadundercut to be cut by means of an additional actuator to ensureadditional effects. The grindstone may also be subjected to oscillatingmovement during grinding.

Finally, it shall be stated that grindstones 1 might be dressed in thesame kind for different types of skis. In this case, of course, therunning surface structure to be selected for the relevant type of skimust be considered, as there are different requirements, for example,for alpine skis, than there are for snowboards, cross-country skis orjumping skis.

What is claimed is:
 1. Facility for dressing a grindstone for grinding arunning surface structure of a ski, the grindstone having acircumferential surface comprising a rotating drive for the grindstone,a dresser adjustable to the circumferential surface of the grindstoneand equipped with at least one cutting insert, a feed drive for movingthe dresser axially parallel relative to the grindstone, and acontrolling system for the feed drive and/or the rotating drive with amemory of a central program selectable via an input unit and with anevaluation circuit connected to the control program memory for aprogram-sensitive definition of position-dependent switching points forthe rate of the feed drive and/or the rotating drive.
 2. Facilityaccording to claim 1, wherein the evaluation circuit is connected to aprogram data memory for characteristic data for the control program, tobe preset as a function of a relevant selected control program via theinput unit.
 3. Facility according to claim 1, wherein the controllingsystem is connected to position switches for the feed drive arrangedalong the axial length of the grindstone.